To assess the prevalence of low serum levels of HDL cholesterol (HDL-C) and its relationship with the presence of cardiovascular disease (CVD) in patients with type 2 diabetes mellitus (DM) and arterial hypertension attended in Internal Medicine and Nephrology offices.Cross-sectional, multicenter study, conducted in diabetic patients with hypertension, aged/= 55 years old. Demographic, clinical and biochemical data were obtained from the patient's hospital records. Low HDL-C was defined as40 mg/dl (men) or46 mg/dl (women). The relationship between low HDL-C and CVD was assessed using logistic regression models.In 2,021 patients (mean age: 68.6 years, 48.9% women, 51.1% with established CVD), the prevalence of low HDL-C was 33.7% (95% CI: 31.5-35.7), it being higher in women (38.0%) than in men (29.6%, p0.001), and higher in patients with previous CVD (37.3% vs. 29.9% in patients without CVD, p=0.001). In the multivariate analysis that included cardiovascular risk factors, an independent relationship between low HDL-C levels and CVD was observed (OR for CVD in patients with low HDL-C: 1.46 [CI 95%: 1.19-1.79, p0.001]), compared to patients with normal HDL-C blood levels. A second model which was also adjusted for left ventricular hypertrophy and renal disease showed a similar association (OR 1.55 [1.21-2.00], p=0.001). This association was stronger in women than in men.One out of three patients with diabetes and hypertension examined in Internal Medicine and Nephrology outpatient offices had low serum levels of HDL-C. Low HDL-C showed an independent relationship with a higher prevalence of CVD.